The present invention relates to an induction device.
Generally, a ferrite core and a dust core are used for an induction device such as a reactor and a transformer. In the case of a ferrite core, the DC superposition characteristic can be ensured by providing an air gap between the cores. However, the provision of the air gap invites an increased loss of magnetic flux. In the case of a dust core, on the other hand, the number of winding turns of a coil need be increased due to a low magnetic permeability of a powder for the dust core, so that copper loss tends to be increased. Japanese Patent Application Publication 2009-278025 discloses a thin choke coil as an induction device that is made of a ferrite core and a dust core to solve the above problem.
The induction device disclosed by the Publication includes a rectangular frame-like ferrite core and an I type dust core having a coil wound therearound and inserted in the ferrite core. The induction device of such structure ensures the DC superposition characteristic without providing any air gap between the cores and prevents an increase in the number of winding turns of a coil.
In a composite magnetic core including a ferrite core and a dust core, the saturation magnetic flux density of the ferrite core changes depending on the temperature, so that the ferrite core should preferably be cooled by fixing the ferrite core to a radiator.
The choke coil of the Publication may be cooled by mounting a cooling radiator to the choke coil. For this purpose, the ferrite core of the choke coil may be formed so as to eliminate the opening on the side of the ferrite core that is opposite from the side where dust core is inserted and a radiator may be mounted to the side of the ferrite core where the opening is eliminated. For cooling the coil as well as the dust core, however, an additional radiator need be mounted to the choke coil on the dust core side thereof. The provision of the additional radiator makes the structure of the choke coil complicated.
If the radiator is fixed to a side surface of the ferrite core, end surface of the coil can be cooled from the side surface of the ferrite core by the radiator. In the above choke coil, the dust core having a coil wound therearound need be assembled to the ferrite core from a lateral side of the ferrite core. However, this manner of assembling is troublesome.
The present invention is directed to providing an induction device having a first core and a second core wound therearound with a coil, wherein the first core and the coil can be cooled from the same direction and the manufacturing can be performed easily.